Method for producing a radiator box or charge air cooler box

ABSTRACT

The invention relates to a method for producing a radiator box or charge air cooler box in the form of a plastic box with an integrated seal by means of two-component injection molding using an injection molding tool. The injection molding tool includes a first main part, a second main part and a movable sliding element core as the third main part, the parts forming a first cavity for at least one part of the plastic box and, by a relative movement of the movable sliding element core, a second cavity, immediately adjacent to the first cavity, for a seal material.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 102014 101143.0, filed on Jan. 30, 2014, the disclosure of which isincorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The invention relates to a method for producing a radiator box or chargeair cooler box in the form of a plastic box with an integrated seal. Theinvention further relates to a radiator box or charge air cooler box inthe form of a plastic box with an integrated seal which is obtainable bythe method according to the invention.

BACKGROUND

Radiator tanks or charge air cooler tanks are manufactured by injectionmolding technical thermoplastics, for example using a glass fiber-filledpolyamide, for example PA66-GF30. The seal is produced separately,likewise by injection molding, for example using a terpolymer elastomer(rubber) of synthetic ethylene propylene diene rubber, abbreviated EPDM.The components are then assembled together with the heat exchanger,which is made of aluminum, for example. WO 2008/030015 A1 and KR 2008 0021 32 8 A describe process chains for integrating the seal, in whichthe radiator tank or charge air cooler tank, produced in advance, isplaced in an additional tool to form a cavity therein for the seal. Aprimer is injected into this die cavity, followed by liquid siliconerubber, abbreviated LSR. EP 2 093 040 A1 describes an injection moldingprocess comprising two process steps, in which a plurality of slidingelements are pulled in the main opening direction and in the lateraldirection in order to open up the second cavity.

The process currently used most frequently for producing tank and sealrequires that the components be produced separately. The assembly of thecomponents further involves a certain amount of control expenditure. Theprocesses described in the aforementioned documents result in anassembly module. Sufficient adhesion of the elastomer is achieved inthese processes by using a primer as an adhesion promoter. With theinjection molding variant presented, a plurality of sliding elements isrequired. Smooth joining faces are involved. A secure adhesion of theseal material is achieved through a lateral form-fitting connection.

SUMMARY

The object of the present invention consists in providing the simplestpossible process for producing a radiator box or charge air cooler boxhaving a seal.

The object of the invention is attained with a method for producing aradiator box or charge air cooler box according to claim 1. According tothe invention, a radiator box or charge air cooler box is produced inthe form of a plastic box having an integrated seal by means oftwo-component injection molding, using an injection molding tool whichcomprises a first main part, a second main part and a movable slidingelement core as a third main part, which parts form a first cavity forat least one part of the plastic box and, by executing a relativemovement of the movable sliding element core, a second cavity,immediately adjacent to the first cavity, for a seal material.

In the method:

-   -   a) the plastic box is produced by injection molding plastic into        the first cavity, and the movable sliding element core is        initially positioned such that it abuts the first cavity and        fills in the second cavity such that no plastic can enter the        second cavity,    -   b) once a holding pressure phase has ended and the plastic box        has cooled sufficiently, the sliding element core is displaced        in the injection molding tool in the main tool opening        direction—away from the abutting first cavity—such that the        second cavity is opened up, and    -   c) a seal material is injected into the second cavity.

Within the context of the present invention, the main tool openingdirection is understood as the opening movement that opens up the cavityfor the plastic box, perpendicular to the contact face between the firstand second main parts.

The advantages of the present invention consist in the integration ofthe seal into the plastic box, which results in a defined fixation andfacilitated assembly. The plastic box for the radiator or charge aircooler is produced with a seal in a single production process. Theseparate production of the seal and the increased assembly and controlexpense for three components are thereby eliminated. This results in aminimization of handling of components and tool parts. With respect tothe seal contour, the tool design provides a sliding element core whichhas a short stroke in the main tool opening direction. Particularlyadvantageous is an embodiment of the invention in which the outercontour of the seal that will later be integrated is determined by theshape of the sliding element core end face that points in the directionof the first cavity.

A particular advantage of the invention is that it enables the form ofthe functional surface of the tank base of the plastic box and the sealto be determined. For instance, the contour of this tank base, that isthe lower part of a wall of the plastic box to be produced, and of theseal can first be embodied as inverted. The resulting seal contour isadvantageously embedded into a groove, that is, a certain part of theseal is integrated into the tank and/or the plastic box. This results ina forth-fitting connection, in addition to a certain adhesiveconnection, and thereby a certain retaining force of the seal on theplastic box, which is of sufficient strength to withstand the subsequenthandling of the components and the tool.

The seal material for producing the seal can advantageously be fed invia at least one connection in the main tool opening direction or alsolaterally via at least one connection in the region of the dividing linebetween the fixed and movable main parts, that is, between the first andsecond main parts of the injection molding tool.

The radiator box or charge air cooler box is preferably produced byinjection molding using thermoplastics, preferably technicalthermoplastics. According to a particularly preferred embodiment, aglass fiber-filled polyimide, for example PA66-GF30, is used as thetechnical thermoplastic for producing the radiator box or charge aircooler box. A material having a polypropylene base, for example PP-GF30,can also be used as the thermoplastic for producing the radiator box orcharge air cooler box.

The end face seal contour can be designed as semicircular in shape, ashas heretofore been standard; this allows the end face seal to achieve acertain tolerance compensation for the material of the heat transferelement that will subsequently be installed, and which in most cases ismade of aluminum. According to an advantageous embodiment of theinvention, curing molding compounds are used as the seal material. Acuring seal material is preferably fed in while heat is simultaneouslyapplied. When curing molding compounds, for example ethylene propylenediene rubber (EPDM), liquid silicone rubber (LSR) or fluorocarbon rubber(FKM), are used as the seal material, the still very high surfacetemperature of the solidified but not yet fully cooled plastic box canbe used for curing. The demolding temperature of PA66-GF30 isapproximately 220° C., for example.

The tool concept according to the invention can also be used forprocessing polyurethane (PUR) in a closed tool. Thus a one-component ortwo-component polyurethane molding compound (PUR) can likewise be usedas the seal material.

A thermoplastic elastomer (TPE) can also be processed likewise as theseal material in the form described here. In this case, the sealmaterial is fed in while heat is simultaneously removed.

According to an advantageous embodiment of the invention, the secondmain part of the injection molding tool and the sliding element core aremade of tool materials having different thermometric conductivities,with the sliding element core having a higher thermometric conductivitythan the second main part of the injection molding tool. Using toolmaterials that have different thermometric conductivities allows thedifferent requirements of thermoplastic or elastomeric processing to betaken into consideration.

A further aspect of the invention relates to a radiator box or chargeair cooler box in the form of a plastic box having an integrated seal,which is obtainable in one of the above-described embodiments by amethod according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, features and advantages of the invention are found inthe following description of embodiment examples with reference to theattached set of drawings. The drawings show:

FIG. 1: an example of a radiator box or charge air cooler box of theprior art,

FIGS. 2A-2C: a schematic representation of the sequence of steps in atwo-component injection molding process involving integration of a seal,and

FIGS. 3A-3C: a schematic representation of the sequence of steps in atwo-component injection molding process involving integration of a sealusing heating elements.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an example of a radiator box or charge air cooler box madeof plastic and having a peripheral seal, according to the prior art.This plastic box is highly complex, that is, designed with amultiplicity of integrated functions. Corresponding injection moldingtools are required for producing the plastic box. In most cases the sealis produced separately with a constant cross-sectional shape.

Various tool concepts exist for the two-component method. The so-calledserial process involves injecting a hard component for the plastic box,and subsequently processing said plastic box. The fully cooled materialis then introduced into an elastomer tool, and a soft component, anelastomer, is molded over said material. In each case, this process issuitable for only a similar box design, and producing the seal is highlycostly.

The so-called integrated process is distinguished from the above serialprocess. According to one variant of this integrated process, the hardcomponent can first be injected into a first cavity, then transferred toa second cavity, for example by means of rotation, and in a second step,the seal material is processed in the second cavity. The tool that isrequired for this must be very large as compared with other injectionmolding tools, and the process as a whole appears to be highly costly.

The invention applies a different form of the integrated process as thetool concept. In this case, the hard component is injected, after whicha second cavity integrated into the tool is opened up and the softcomponent, for example an elastomer, is injected, with both injections,that of the thermoplastic and that of the elastomer, therefore beingcarried out within a single injection cycle in a single tool.

With this variant of the integrated process, although the toolcomplexity is greater than that of injection molding tools used forserial processing of thermoplastics, it is still manageable. This formof the integrated process requires a corresponding machine, and requiresa slight increase in overall cycle time over that of the one-componentprocess.

FIGS. 2A-2C show a schematic representation of the sequence of steps inan integrated two-component injection molding process. FIG. 2A shows aninjection molding tool 1 with a fixed, first main part 1 a, a movable,second main part 1 b and a movable sliding element core 1 c as a thirdmain part of the injection molding tool 1. Depending on the geometry ofthe injection molded box to be produced, it can also be advantageous forthe first main part 1 a to be embodied as movable, and for the secondmain part 1 b to represent the fixed side of the tool. The second mainpart 1 b of injection molding tool 1 provides a groove-like receivingspace 2 for the lower part of a wall of the radiator box or charge aircooler box and/or a plastic box 3 to be produced, also called the tankbase. In most cases, a base surface 4 of the receiving space 2 liesbelow a dividing line 5 between the first main part 1 a and the secondmain part 1 b of the injection molding tool 1. A channel-like guidespace 6 for the sliding element core 1 c, which is vertically movableaccording to FIGS. 2A-2C, extends from the base surface 4. Thedimensions of the sliding element core 1 c perpendicular to adisplacement direction or a main tool opening direction 7 of the slidingelement core 1 c correspond to the corresponding dimensions of the guidespace 6. An end face 8 pointing in a direction of the receiving space 2,which the end face has a concave shape according to FIG. 2A, determinesan outer contour 10 of a seal or a seal material 9 that will later beintegrated. As represented in FIG. 2C, the outer contour 10 is embodiedas correspondingly convex.

According to FIG. 2A, the movable sliding element core 1 c is initiallypositioned such that it fills up at least a part of the guide space 6that is immediately adjacent to the receiving space 2, and such that itprojects into the receiving space 2, wherein a part of the receivingspace 2 that is not filled up by the sliding element core 1 c forms afirst cavity 11, namely for the injection molding of the thermoplasticmaterial of the plastic box 3. FIG. 2A shows the phase of the process inwhich the plastic box 3 made of thermoplastic material has been producedin the first cavity 11 by means of injection molding. Once a holdingpressure phase has ended and the plastic box 3 has cooled sufficiently,the sliding element core 1 c, as shown in both FIG. 2B1 and FIG. 2B2, isdisplaced out of the receiving space 2 into the guide space 6. As aresult, a second cavity 12 is opened up, which according to therepresentation of FIG. 2B1 and FIG. 2B2, extends into the guide space 6.The displacement direction 7 corresponds to the main tool openingdirection 7. The second cavity 12 is provided for receiving theso-called soft component, seal material 9. The seal material 9 can befed in via a connection 13 a in the main tool opening direction 7, asrepresented in FIG. 2B1. Alternatively, the seal material 9 is fed inlaterally via a connection 13 b in the region of the dividing line 5, inthe illustrated embodiment example, below the dividing line 5, asrepresented in FIG. 2B2.

FIG. 2C shows the seal material 9 injected into the second cavity 12.The convex outer contour 10 of the resulting seal material 9 correspondswith the concave contour of the end face 8 at an upper end of thesliding element core 1 c, as is clear from a comparison of FIGS. 2B1-2C.

As is represented schematically in FIGS. 3A-3C, the curing seal material9 is advantageously fed in while heat is simultaneously applied. Forthis purpose, heating elements 14 can be integrated into the injectionmolding tool 1, as shown in FIGS. 3A-3B, with the heating elements 14being activated during the infeeding of the seal material 9 as shown inFIG. 3B. The heating elements 14 are positioned in the second main part1 b close to the walls of the guide space 6, that is, around the guidespace 6. The second main part 1 b is made of a material that has a lowerthermometric conductivity than the material of the sliding element core1 c. The material of the sliding element core 1 c advantageously has ahigh thermometric conductivity, in order to transmit heat to the sealmaterial 9 which is fed into the second cavity 12. Embodying theinjection molding tool 1 with materials having different thermometricconductivities enables a thermal separation of the regions for producingthe plastic box 3 on one hand and the seal material 9 on the other. Arapid curing of the seal material 9 can thereby be achieved, ifnecessary. If curing molding compounds are used, good heat conductionvia the sliding element core 1 c can thus support thetemperature-dependent curing process of the seal material 9, while atthe same time, the supply of heat to the material of the alreadysolidified thermoplastic box is kept low due to the poorer heatconducting properties of the material of the second main part 1 b. Incontrast, if non-curing molding compounds are used, an intensive coolingof this region can occur, in order to rapidly dissipate the heat in thisarea.

FIG. 3C shows a schematic illustration of a “base” of the plastic box 3with the cured seal material 9. The resulting seal material 9, as shownin FIG. 3C, is embedded in a groove between two base arms 15 of theplastic box 3. In addition to a certain adhesive connection, aform-fitting connection is thereby produced, and as a result, a certainretaining force of the seal material 9 on the plastic box 3, which issufficient to withstand subsequent handling.

LIST OF REFERENCE SIGNS

-   1 injection molding tool-   1 a first main part, main part (fixed)-   1 b second main part (movable), main part-   1 c (movable) sliding element core, third main part, main part-   2 receiving space-   3 radiator box or charge air cooler box, plastic box-   4 base surface-   5 dividing line-   6 guide space-   7 displacement direction, main tool opening direction-   8 end face-   9 seal, seal material, seal contour-   10 outer contour (of seal 9)-   11 first cavity-   12 second cavity-   13 a connection in main tool opening direction 7-   13 b connection below dividing line 4, connection in the region of    the dividing line-   14 heating elements-   15 base arms

1-14. (canceled)
 15. A method for producing a plastic box with anintegrated seal for at least one of a radiator and a charge air coolercomprising the steps of: providing an injection molding tool including afirst main part, a second main part, and a movable sliding element core,the first main part, the second main part, and the movable slidingelement core cooperating to form a first cavity and a second cavityadjacent the first cavity configured to receive a seal material; movingthe movable sliding element core within the second cavity to an initialposition to abut the first cavity and seal the second cavity; injectinga plastic into the first cavity by an injection molding process;permitting a holding pressure phase of the injection molding process toend and the plastic to substantially cool; moving the movable slidingelement core in a main tool opening direction away from the initialposition to open the second cavity; and injecting a seal material intothe second cavity to form the integrated seal of the plastic box. 16.The method according to claim 15, wherein the movable sliding elementcore includes an end face having a shape corresponding to a shape of anouter contour of the integrated seal.
 17. The method according to claim15, wherein the step of injecting the seal material into the secondcavity includes the step of feeding the seal material through at leastone connection in the main tool opening direction.
 18. The methodaccording to claim 15, wherein the step of injecting the seal materialinto the second cavity includes the step of feeding the seal materialthrough at least one connection in a direction lateral to the main toolopening direction, wherein the at least one connection is disposed in aregion adjacent a dividing line, the dividing line intermediate thefirst main part and the second main part of the injection molding tool.19. The method according to claim 15, wherein the plastic is athermoplastic.
 20. The method according to claim 19, wherein thethermoplastic is at least one of a glass fiber-filled polymide and apolypropylene based material.
 21. The method according to claim 20,wherein the thermoplastic is PA66-GF30.
 22. The method according toclaim 20, wherein the thermoplastic is PP-GF30.
 23. The method accordingto claim 15, wherein the seal material is a curing molding compound. 24.The method according to claim 15, wherein the seal material is one ofethylene propylene diene rubber, liquid silicone rubber, andfluorocarbon rubber.
 25. The method according to claim 15, wherein thestep of injecting the seal material into the second cavity includes thestep of applying heat to the seal material.
 26. The method according toclaim 15, wherein the seal material is one of a one-componentpolyurethane molding compound and a two-component polyurethane moldingcompound.
 27. The method according to claim 15, wherein the sealmaterial is a thermoplastic elastomer.
 28. The method according to claim15, wherein the step of injecting the seal material into the secondcavity includes the step of removing heat from the seal material. 29.The method according to claim 15, wherein the second main part has athermometric conductivity different from a thermometric conductivity ofthe movable sliding element core.
 30. The method according to claim 29,wherein the thermometric conductivity of the sliding element core isgreater than the thermometric conductivity of the second main part. 31.A plastic box with an integrated seal configured for one of a radiatorand a charge air cooler formed by the method of claim 15.